U.S. patent number 7,429,332 [Application Number 11/119,956] was granted by the patent office on 2008-09-30 for separating constituents of a fluid mixture.
This patent grant is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to Timothy H. Hunter, Jim B. Surjaatmadja.
United States Patent |
7,429,332 |
Surjaatmadja , et
al. |
September 30, 2008 |
Separating constituents of a fluid mixture
Abstract
A device for separating constituents of a fluid mixture includes
an elongate vessel oriented at an acute angle to horizontal. The
vessel is operable to receive the fluid mixture and direct the
fluid mixture to flow in a convection cell spanning substantially a
length of the vessel. The convection cell is formed by
gravitational forces acting on the fluid mixture and is operable to
deposit a heavy constituent of the fluid mixture about a lower end
of the vessel and a light constituent of the fluid mixture about an
upper end of the vessel.
Inventors: |
Surjaatmadja; Jim B. (Duncan,
OK), Hunter; Timothy H. (Duncan, OK) |
Assignee: |
Halliburton Energy Services,
Inc. (Houston, TX)
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Family
ID: |
37308602 |
Appl.
No.: |
11/119,956 |
Filed: |
May 2, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060000608 A1 |
Jan 5, 2006 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10881223 |
Jun 30, 2004 |
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Current U.S.
Class: |
210/799; 210/256;
210/540; 210/801; 210/532.1; 210/519; 210/299; 210/804; 210/DIG.5;
210/170.01 |
Current CPC
Class: |
B01D
17/0214 (20130101); B01D 21/0012 (20130101); B01D
21/0015 (20130101); B01J 19/32 (20130101); E21B
43/305 (20130101); E21B 43/38 (20130101); B01D
21/003 (20130101); Y10S 210/05 (20130101); B01J
2219/32279 (20130101) |
Current International
Class: |
B01D
17/025 (20060101) |
Field of
Search: |
;210/747,799,800,801,804,253,254,256,170.01,DIG.5,299,265,538,540,532.1,519 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2 326 895 |
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Jan 1999 |
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GB |
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WO 96/03566 |
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Feb 1996 |
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WO |
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WO 97/25150 |
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Jul 1997 |
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WO |
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WO 98/37307 |
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Aug 1998 |
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WO |
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WO 98/41304 |
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Sep 1998 |
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WO |
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WO 00/65197 |
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Nov 2000 |
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WO |
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WO 01/23707 |
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Apr 2001 |
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WO |
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WO 02/14647 |
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Feb 2002 |
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WO |
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WO 03/062597 |
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Jul 2003 |
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WO |
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WO 2004/053291 |
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Jun 2004 |
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WO |
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Other References
SP. Engel and Phil Rae, "New Methods for Sand Cleanout in Deviated
Wellbores Using Small Diameter Coiled Tubing," IADC/SPE 77204,
Society of Petroleum Engineers, Copyright 2002, 6 pages. cited by
other .
Jim B. Surjaatmadja, "Well Intervention Using Coiled Tubing for
Sweep-Cleaning Out of Deviated Wellbores and Accurate Placement of
Multiple Fractures in Vertical and Deviated Wellbores," 10.sup.th
European Coiled Tubing and Well Intervention Roundtable,
International Coiled Tubing Association, Society of Petroleum
Engineers, Nov. 16-17, 2004, 10 pages. cited by other .
Surjaatmadja, et al., U.S. Patent Application entitled "Wellbore
Completion Design to Naturally Separate Water and Solids From Oil
and Gas," U.S. Appl. No. 10/881,223, filed Jun. 30, 2004 (26
pages). cited by other .
Jim B. Surjaatmadja & R. Rosine, "An Effective Sweep--Cleaning
of Large Deviated Wellbores Using Small Coiled-Tubing Systems",
2005 SPE/ICoTA Coiled Tubing Conference and Exhibition, Apr. 12-13,
2005, 8 Pages. cited by other .
Office Action dated Aug. 25, 2006 for U.S. Appl. No. 10/881,223.
cited by other .
Final Office Action dated Feb. 22, 2007 for U.S. Appl. No.
10/881,223. cited by other .
Advisory Action dated May 31, 2007 for U.S. Appl. No. 10/881,223.
cited by other .
Notice of Allowance dated Jul. 13, 2007 for U.S. Appl. No.
10/881,223. cited by other .
Notice of Allowance and Fees Due dated Oct. 30, 2007 for U.S. Appl.
No. 10/881,223. cited by other .
International Search Report and Written Opinion dated Sep. 27, 2007
for application serial No. PCT/US2006/016724. cited by
other.
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Primary Examiner: Upton; Christopher
Attorney, Agent or Firm: Morico; Paul
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of pending application
Ser. No. 10/881,223 filed Jun. 30, 2004, the disclosure of which is
incorporated herein by reference in its entirety.
Claims
What is claimed is:
1. A device for separating constituents of a fluid mixture,
comprising an elongate vessel oriented at an acute angle to
horizontal, wherein: the vessel is operable to receive the fluid
mixture through an inlet port and direct the fluid mixture to
convectively flow in a convection cell spanning substantially a
length of the vessel; the convection cell is formed by
gravitational forces acting on the fluid mixture; and the
convection cell is operable to deposit a heavy constituent of the
fluid mixture about a lower end of the vessel and a light
constituent of the fluid mixture about an upper end of the vessel,
wherein the acute angle to horizontal is between about 30.degree.
and about 70.degree.; and wherein the disposition of the inlet port
is selected from the group consisting of at an acute angle to the
vessel and in a plane coaxial the axis of rotation of the
convective flow.
2. The device of claim 1 further comprising a first outlet about
the upper end and a second outlet about the lower end.
3. The device of claim 2 further comprising an inlet between the
first and second outlets.
4. The device of claim 3 further comprising a filter residing at
least partially between the inlet and the first outlet or at least
partially between the inlet and the second outlet.
5. The device of claim 4 wherein the filter is adapted to pass
water and filter oil.
6. The device of claim 1 further comprising a filter, wherein the
convection cell operates to separate at least a portion of a
constituent from the fluid mixture prior to passage of the fluid
mixture through the filter.
7. The device of claim 6 wherein the filter comprises at least one
of a membrane or a prepacked screen.
8. The device of claim 7 further comprising a bypass adapted to
selectively allow fluid to bypass the filter.
9. The device of claim 1 further comprising a second elongate
vessel oriented at an acute angle to horizontal, wherein: the
second vessel is operable to receive a fluid mixture output from
the first mentioned vessel and direct the fluid mixture output to
flow in a convection cell spanning substantially a length of the
second vessel; and the second vessel is operable to deposit a heavy
constituent of the fluid mixture output about a lower end of the
second vessel.
10. The device of claim 9 wherein the first mentioned vessel and
the second vessel are substantially helical and nested with one
another.
11. The device of claim 9 wherein the first mentioned vessel and
the second vessel are substantially linear and nested with one
another.
12. The device of claim 1 further comprising a second elongate
vessel oriented at an acute angle to horizontal, wherein the second
vessel is operable to receive a portion of the fluid mixture.
13. The device of claim 1, wherein the acute angle to the vessel is
between about 30.degree. and about 70.degree..
14. A fluid separator, comprising an elongate receptacle having an
inlet operable to receive a fluid mixture, wherein: the receptacle
is oriented at an angle to horizontal such that gravitational force
causes a portion of the fluid mixture to settle to a lower sidewall
of the receptacle, flow along the lower sidewall to a lower end
wall of the receptacle, and turn at the lower end wall to flow
along an upper sidewall of the receptacle toward an upper end of
the receptacle; and the flow along the lower sidewall has a larger
amount of a heavy constituent of the fluid mixture than the flow
along the upper sidewall, wherein the angle to horizontal is
between about 30.degree. and about 70.degree.; and wherein the
inlet is disposed one of at an acute angle to the elongate
receptacle or in a plane coaxial with axis of rotation of the fluid
mixture.
15. The fluid separator of claim 14 further comprising an outlet
about the upper and operable to output a portion of the fluid
mixture containing less heavy constituent than the fluid mixture
introduced through the inlet.
16. The fluid separator of claim 14 further comprising a filter
residing at least partially between the inlet and the upper end or
at least partially between the inlet and the lower end.
17. The fluid separator of claim 14 wherein the receptacle is an
elongate cavity formed in the Earth adjacent a well.
18. The fluid separator of claim 14 wherein a length to width
aspect ratio of the receptacle is at least about 2:1.
19. The device of claim 14, wherein the acute angle is between
about 30.degree. and about 70.degree..
20. A method of separating constituents of a fluid mixture,
comprising receiving the fluid mixture through an inlet port in an
elongate receptacle oriented at an acute angle to horizontal such
that gravitational force causes a portion of the fluid mixture to
settle to a lower sidewall of the receptacle, flow along the lower
sidewall to a lower end wall of the receptacle, and turn at the
lower end wall to flow along an upper sidewall of the receptacle
toward an upper end of the receptacle, wherein the flow along the
lower sidewall has a larger amount of a heavy constituent of the
fluid mixture than the flow along the upper sidewall, wherein the
acute angle to horizontal is between about 30.degree. and about
70.degree.; and wherein the inlet port is disposed one of at an
acute angle to the elongate receptacle or in a plane coaxial with
axis of rotation of the fluid mixture.
21. The method of claim 20 further comprising withdrawing a portion
of the fluid mixture from the upper end, wherein the withdrawn
portion has less heavy constituent than the fluid mixture initially
received in the receptacle.
22. The method of claim 20 further comprising withdrawing a portion
of the fluid mixture from a lower end of the receptacle, wherein
the withdrawn portion has more heavy constituent than the fluid
mixture initially received in the receptacle.
23. The method of claim 20 further comprising filtering a
constituent from at least one of the portion of the fluid mixture
flowing along the lower sidewall or the portion of the fluid
mixture flowing along the upper sidewall.
24. The method of claim 23 wherein filtering the constituent
comprises filtering oil from the fluid mixture flowing along the
lower sidewall.
25. The method of claim 23 wherein filtering the constituent
comprises passing the portion of the fluid mixture through at least
one of an ionically treated membrane, a molecularly sized porous
membrane, or a prepacked screen.
26. The method of claim 20 further comprising: withdrawing a
portion of the fluid mixture from at least one of the upper end or
the lower end of the receptacle; and receiving the portion of the
fluid mixture in a second elongate receptacle oriented at an acute
angle to horizontal such that gravitational force causes a portion
of the fluid mixture to settle to a lower sidewall of the second
receptacle, flow along the lower sidewall of the second receptacle
to a lower end wall of the second receptacle, and turn at the lower
end wall of the second receptacle to flow along an upper sidewall
of the second receptacle toward an upper end of the second
receptacle, wherein the flow along the lower sidewall of the second
receptacle has a larger amount of a heavy constituent of the fluid
mixture than the flow along the upper sidewall of the second
receptacle.
Description
BACKGROUND
This disclosure relates to separating constituents of a fluid
mixture, and more particularly to systems and methods for
separating constituents of a fluid mixture having disparate
densities.
In many industries, there is a need to separate a fluid mixture
into one or more of its constituents. For example, in producing
hydrocarbons from a well, water and particulate solids, such as
sand, are produced together with the hydrocarbons. It is not
desirous to have either of these byproducts present in the
hydrocarbons. Therefore, well operators have implemented numerous
techniques to separate the water and sand from the produced
hydrocarbons.
One conventional technique for removing sand from the hydrocarbons
is to install sand screens in the production pipe inside the well
bore. A sand screen is screen including one or more layers of mesh
sized to prevent passage of sand into an interior of the screen.
Sand screens have been used successfully for many years; however,
like any filter, they are subject to clogging and plugging, for
example, as the screen's mesh fills with sand and other
particulate.
In the past, water has been filtered from the produced hydrocarbons
or separated in a free-water knockout separator. Filters, like sand
screens, are prone to clogging and plugging. Free-water knockout
separators are large vessels that separate the water and
hydrocarbons by allowing the water to settle vertically downward
and out of the hydrocarbons. The separated water is subsequently
withdrawn from the bottom of the vessel. Free-water knockout
separators are generally slow at separating the water from
hydrocarbons, because they rely on the water settling vertically
downward and out of the hydrocarbons.
Accordingly, there is a need for improved systems and methods of
separating constituents of a fluid mixture.
SUMMARY
The present disclosure is directed to systems, devices and methods
for separating constituents of a fluid mixture.
One illustrative implementation encompasses a device for separating
constituents of a fluid mixture. The device includes an elongate
vessel oriented at an acute angle to horizontal. The vessel is
operable to receive the fluid mixture and direct the fluid mixture
to flow in a convection cell spanning substantially a length of the
vessel. The convection cell is formed by gravitational forces
acting on the fluid mixture and is operable to deposit a heavy
constituent of the fluid mixture about a lower end of the vessel
and a light constituent of the fluid mixture about an upper end of
the vessel.
In some implementations, the device includes a second elongate
vessel oriented at an acute angle to horizontal. The second vessel
is operable to receive a fluid mixture and direct the fluid mixture
to flow in a convection cell spanning substantially a length of the
second vessel. The convection cell is formed by gravitational
forces acting on the fluid mixture and is operable to deposit a
heavy constituent of the fluid mixture about a lower end of the
second vessel. The fluid mixture received by the second vessel can
include either or both of a fluid mixture output from the first
mentioned vessel or the fluid mixture provided to the first
mentioned vessel can be split between the first mentioned vessel
and the second vessel. The first and second elongate vessels can be
nested to reduce the space required for the device.
Some implementations can incorporate a filter residing at least
partially between the inlet and an outlet near the upper end or
between the inlet and an outlet near the lower end. More than one
filter can be provided, for example one between the inlet and the
outlet near the upper end and one between the inlet and the outlet
near the lower end. The convection cell can operate to separate at
least a portion of a constituent from the fluid mixture prior to
passage of the fluid mixture through the filter. In some instances
the filter can include a membrane or a prepacked screen. A bypass
can be provided to selectively allow fluid to bypass the
filter.
Another illustrative implementation encompasses a fluid separator.
The fluid separator includes an elongate receptacle having an inlet
operable to receive a fluid mixture. The receptacle is oriented at
an angle to horizontal such that gravitational force causes a
portion of the fluid mixture to settle to a lower sidewall of the
receptacle. That portion of the fluid flows along the lower
sidewall to a lower end wall of the receptacle and turns at the
lower sidewall to flow along an upper sidewall of the receptacle
toward an upper end of the receptacle. The flow along the lower
sidewall has a larger amount of a heavy constituent of the fluid
mixture than the flow along the upper sidewall.
Yet another illustrative implementation encompasses a method of
separating constituents of a fluid mixture. In the method the fluid
mixture is received in an elongate receptacle oriented at an acute
angle to horizontal such that gravitational force causes a portion
of the fluid mixture to settle to a lower sidewall of the elongate
receptacle. That portion flows along the lower sidewall to a lower
end wall of the elongate receptacle and turns at the lower end wall
to flow along an upper sidewall of the elongate receptacle towards
an upper end of the receptacle. The flow along the lower sidewall
has a larger amount of heavy constituent of the fluid mixture than
the flow along the upper sidewall.
An advantage of some implementations is that efficient separation
of fluid mixture constituents can be achieved without additional
energy input. Gravitational forces can be the primary driver for
separation; and therefore there are no operational costs associated
with energy input. However, because of the convective flow
separation, the implementations perform separation more quickly
than traditional separators relying primarily on constituents
settling vertically out of the fluid mixture. The convective flow
separation also does not require high velocity fluid flow often
required by other traditional separators (like cyclonic separators)
which often cause formation of inseparable emulsions.
Another advantage of some implementations is that multiple
separation vessels can be used in parallel to increase separation
capacity. Multiple separation vessels can be used in series to
separate multiple constituents of a fluid mixture. The multiple
separation vessels can be nested in a space efficient manner.
Another advantage of some implementations is that one or more
separation vessels can be used in conjunction with a filter to
reduce the filtering load the filter must bear. Such reduced
filtering load increases the life of the filter and reduces
clogging.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic side cross-sectional view of an illustrative
separator constructed in accordance with the invention;
FIG. 2A is a schematic side view of a plurality of illustrative
separators constructed in accordance with the invention and
arranged in a nested configuration;
FIG. 2B is a schematic side view of the illustrative separators of
FIG. 2A configured in series;
FIG. 2C is a schematic side view of the illustrative separators of
FIG. 2A configured in parallel;
FIG. 3A is a schematic side view of another illustrative separator
constructed in accordance with the invention;
FIG. 3B is a schematic side view of the illustrative separator of
FIG. 3A depicted in an illustrative sub-surface application in
accordance with the invention;
FIG. 4 is a schematic side cross-sectional view of another
illustrative separator constructed in accordance with the invention
incorporating a filter; and
FIG. 5 is a schematic side cross-sectional view of another
illustrative separator incorporating a filter constructed in
accordance with the invention.
DETAILED DESCRIPTION
Referring first to FIG. 1, an illustrative separator 100
constructed in accordance with the invention includes an elongate
vessel 110 oriented with its longitudinal axis at an acute angle
.theta. relative to horizontal. As is discussed in more detail
below, the angle .theta. may be different in different
applications. In one instance, angle .theta. is between about
30.degree. and about 70.degree.. Additionally, as is discussed in
more detail below, the length of the vessel 110 is greater than a
transverse dimension, for example diameter, of the vessel 110. In
one instance, the length of the vessel 110 may be greater than
twice or three times the transverse dimension (e.g. diameter). In
one instance, the aspect ratio of the vessel 110 is 2:1 or
greater.
The vessel 110 can include one or more inlet ports 112 through
which a fluid mixture for separation is introduced. The vessel 110
can include one or more outlet ports 114 through which the
separated constituent fluids and particulate can be withdrawn. The
inlet port 112 and outlet port 114 can be in various different
locations. For example, the separator 100 of FIG. 1 includes a
light constituent outlet port 114a about an upper end of the vessel
110 and a heavy constituent outlet port 114b about a lower end of
the vessel 110. In another instance, the inlet port 112 can be near
the bottom of the vessel 110 and the one or more outlet ports 114
can be above the inlet port 112. In yet another instance, the inlet
port 112 can be near the top of the vessel 110 and the one or more
outlet ports 114 below the inlet port 112.
Although depicted in FIG. 1 as exiting a lateral wall of the vessel
110, the outlet ports 114 may exit the vessel 110 elsewhere. For
example, in illustrative separator 200 of FIG. 2A, the outlet ports
114 exit the end walls of the elongate vessel 210. Referring back
to FIG. 1, the inlet port 112 is located intermediate the outlet
ports 114. Although depicted substantially equidistant between the
outlet ports 114, the inlet port 112 may be positioned closer to
one or the other ends of the vessel 110.
The illustrative separators described herein are operable in
separating one or more constituents of disparate density from a
fluid mixture. The fluid mixture can be a mixture of one or more
immiscible fluids, as well as a mixture of one or more fluids and
solids (e.g. particulate). The constituents of disparate density
are referred to herein for convenience of reference as a light
constituent and a heavy constituent of the fluid mixture. In one
instance, for example in an oilfield application, the separators
may be used in separating a fluid mixture of oil and water, where
the heavy constituent is water and the light constituent is oil.
The separators may be used in separating particulate such as
formation fines (e.g. sand) and fracturing proppant from one or
more liquids (e.g. oil and water). In use separating particulate
from oil and/or water, the heavy constituent is particulate and the
light constituent is the oil and/or water. There are many other
mixtures of immiscible fluids and mixtures of fluids and solids to
which the concepts described herein are applicable. For example, in
another instance, such as a beverage manufacturing application, the
separators can be used in separating a fluid mixture including
orange juice (light constituent) and orange pulp (heavy
constituent). Some other examples can include milk and particulate,
paint and particulate, and lubrication oil and contaminates.
In operation, the fluid mixture is input through the inlet port 112
into the interior of the vessel 110. By force of gravity, the heavy
constituents 115 of the fluid mixture begin to sink substantially
vertically downward (substantially parallel to the gravity vector)
and collect about lower sidewall 116 of the vessel 110. This
sinking or vertically downward flow of heavy constituents 115
occurs substantially throughout the length of the vessel 110. The
collecting heavy constituents 115 about the lower sidewall 116
creates a hydrostatic pressure imbalance between the fluid mixture
about upper sidewall 118 of the vessel 110 and the fluid mixture
about the lower sidewall 116, because of the density differential
of the fluid mixtures. As a result, the fluid mixture about the
lower sidewall 116, containing a larger portion of heavy
constituents 115, begins to travel downward along the lower
sidewall 116 and substantially parallel to the longitudinal axis of
the vessel 110. The fluid mixture about the upper sidewall 118,
containing a smaller portion of heavy constituents 115,
correspondingly begins to travel upward along the upper sidewall
118 and substantially parallel to the longitudinal axis of the
vessel 110. The result is a convection cell 120 that spans between
upper end 122 and lower end 124 of the vessel 110; the convection
cell 120 defined by fluid flowing down the lower sidewall 116,
turning at the lower end 124 of the vessel 110, flowing up the
upper sidewall 118 and turning at the upper end 122 of the vessel
110. In addition to the convection cell 120, the substantially
vertically downward flow of heavy constituents 115 continues
substantially throughout the vessel 110.
As the fluid mixture containing a larger portion of heavy
constituents 115 turns at the lower end 124 of the vessel 110 to
flow back upward along the upper sidewall 118, it deposits a
portion of the heavy constituents 115 at the lower end 124 of the
vessel 110. Therefore, the fluid flowing from the lower end 124,
back up the upper sidewall 118 has a reduced portion of heavy
constituents 115. The amount of heavy constituents 115 in the flow
flowing up from the lower end 124 further decreases as the flow
continues back up the upper sidewall 118, because the heavy
constituents 115 continue to sink vertically downward (vertically
downward flow of heavy constituents 115) and join the flow along
the lower sidewall 116. The vertically downward flow of heavy
constituents 115 continues, and continues to join the flow along
the lower sidewall 116 as the flow continues upward to the upper
end 122. No undulations or protrusions are needed on the interior
surface of the vessel 110 to turn or otherwise disturb the fluid
flow to effect the constituent separation.
The convection cell 120 and the vertically downward flow of heavy
constituent 115 operate continuously while fluid is introduced
through the inlet port 112. Therefore, the heavy constituents 115
are separated toward the lower end 124 and the light constituents
toward the upper end 122. The heavy constituents 115 can be
withdrawn through the heavy constituent outlet port 114b near the
lower end 124 of the vessel 110. Likewise, the light constituents
can be withdrawn through the light constituent outlet port 114a
near the upper end 122 of the vessel 110.
It has been found that an angle of inclination (.theta.) between
about 40-60 degrees produces efficient operation, although other
angles also work. Steeper angles are less conducive to convective
action, but may still be operable. Shallower angles, likewise may
still be operable, but generally need longer sidewalls 116. Putting
the increased size of the vessel 110 aside, longer sidewalls 116
also mean more friction; thus reducing effectiveness of the
separation.
Because the fluid circulates within the convection cell 120, the
separator 100 can separate the constituents of a fluid mixture
faster than the heavy constituent 115 can settle vertically
downward and out of the light constituent. Furthermore, no energy
needs to be input into the system to effect the separation other
than the force of gravity. Conventional separators relying solely
on the heavy constituents settling vertically downward and out of
the light constituents are limited by the terminal velocity of the
heavy constituent in the fluid mixture. Once the heavy constituent
reaches its terminal downward velocity, the separation cannot occur
any faster. The convection cell 120 formed by the separator 100,
however, carries the heavy constituent 115 towards the lower end
124 of the vessel 110 at a rate that is faster than the terminal
velocity of the heavy constituent 115. Therefore, the heavy
constituent 115 is transported to the lower end 124 and separated
from the light constituent at a higher rate.
A long, narrow vessel 110 is more efficient at forming a convection
cell 120 than a short, wide vessel. The efficiency of a long,
narrow vessel 110 stems from the pressure in the axis of the
downward flow along the lower sidewall 116 being greater than the
pressure in the axis of the vertically downward flow of heavy
constituent 115 at the point where the flow along the lower
sidewall 116 turns to flow upward. At the lower end 124 of the
vessel 110, the downward flow along the lower sidewall 116 turns
and flows against the vertically downward flow of heavy constituent
115. To form a convection cell 120, the upward flow from the lower
sidewall 116 must overpower the vertically downward flow of heavy
constituents 115. As a transverse dimension of the vessel 110
decreases, the hydrostatic pressure differential in the axis of the
vertically downward flow of heavy constituents 115 is reduced.
Likewise as the length of the vessel 110 increases, the hydrostatic
pressure differential in axis of the downward flow along the lower
sidewall 116 increases. Therefore, as the ratio of length to width
increases, so does the ability of the upward flow from the lower
sidewall 116 to overpower the vertically downward flow of the heavy
constituent 115. Likewise, as the length increases, the fluid
velocity gets higher. This increases friction between the fluid and
the walls, and also between the two opposing fluids. Therefore,
increases in length, beyond a certain length may not increase the
speed of separation. However, increasing the length further would
increase the quality or purity of the separation as separation
continues throughout the length of the vessel
The separator 100 can be configured to be free-standing or linked
to other equipment for above-ground or on-seafloor installations.
Alternately, the separator 100 can be buried below the Earth's
surface. Locating the separator 100 below the Earth's surface not
only preserves the surface for other uses, but protects the
separator 100 from potential damage that may occur when on the
surface. Additionally the separator 100 may be placed inside of a
well bore, or located adjacent one or more wells for use in
separating a fluid mixture associated with the wells. As an
alternative to burying the separator 100, an equivalent structure
to one or more of the vessel 110, inlet port 112, and/or outlet
ports 114 can be bored into the Earth and used as a separator.
Other configurations of separators described herein may also be
buried below the Earth's surface or constructed with equivalent
structures bored into the Earth.
FIG. 2A shows a space efficient manner of co-locating two or more
separators 200. As is shown in the figure, the separators 200 are
substantially linear, and therefore can be placed closely adjacent
one another in a nested arrangement. The separators 200 can be
arranged to operate in series (FIG. 2B), where an outlet 114 of one
separator 200 feeds an inlet 112 of another separator, or the
separators 200 can be arranged to operate in parallel (FIG. 2C),
where a fluid mixture to be separated is distributed among the
inlets 112 of the two or more separators 200. Configuring the
separators 200 in series (FIG. 2B) enables further separation of
one constituent of a fluid mixture into sub-constituents. For
example, a first of two separators 200 in series may separate
particulate and water from oil, and the second of the two
separators 200 may separate the particulate from the water.
FIG. 3A depicts a plurality of alternate illustrative separators
300, each separator 300 substantially helical and configuration. In
a similar manner to the substantially linear separators 200
depicted in FIG. 2A, the substantially helical separators 300 of
FIG. 3A can be placed closely adjacent one another and a nested
arrangement. The separators 300, each have an elongate helical
vessel 310 with an inlet port 312 and one or more outlet ports 314,
for example a light constituent outlet port 314a and a heavy
constituent outlet port 314b. As is best seen in FIG. 3B, the
separators 300 configured in a nested arrangement are suited for
placement within a cylindrical body, such as the conductor casing
316 at or near a subsea wellhead 320.
Turning now to FIG. 4, another alternate illustrative separator 400
incorporates a filter 426. The separator 400 is operable to
separate the heavy and light constituents of a fluid mixture by
establishing a convection cell 420 as is described above with
reference to FIG. 1. However, rather than being the primary
separation mechanism, as above, the convection cell 420 in the
separator 400 operates to initially separate the heavy and light
constituents of the fluid mixture prior to filtration of a portion
of the fluid mixture by the filter 426. By operating to initially
separate the heavy constituents of the fluid mixture prior to
filtration by the filter 426, the convection cell 420 reduces the
filtering load on the filter 426. The reduced filtering load on the
filter 426 reduces clogging and prolongs the life of the filter
426.
The separator 400 includes an elongate vessel 410 having an inlet
port 412 and one or more outlet ports 414, for example a light
constituent outlet port 414a and a heavy constituent outlet port
414b. As above, the light constituent outlet port 414a may be
positioned about an upper end 422 of the vessel 410 and the heavy
constituent outlet port 414b may be positioned about a lower end
424 of the vessel 410. In one illustrative implementation, the
filter 426 may be a membrane that spans, at least partially, across
an interior of the vessel 410. Gaps (not specifically shown) may be
provided in the filter 426 to allow passage of fluid if the filter
426 becomes blocked. In one implementation the filter 426 may be an
ionically treated porous membrane that may also or alternatively be
a molecularly sized porous membrane. The filter 426 may be
positioned above or below the inlet port 412. In the configuration
of FIG. 4, the filter 426 is positioned below the inlet port 412
and oriented to span the interior of the vessel 410 at a diagonal.
One instance where it may be desirable for the filter 426 to be
positioned below the inlet port 412 is a configuration where the
filter 426 filters the light constituent and passes the heavy
constituent. For example, the filter 426 may be oil philic and
hydrophobic to filter oil from water and pass the water. One
instance where it may be desirable for the filter 426 to be
positioned about the inlet port 412 is a configuration where the
filter 426 filters the heavy constituent and passes the light
constituent. For example, the filter 426 may be a fine mesh that
filters particulate from water and/or oil.
Operation of the separator 400 is similar to the separator 100 of
FIG. 1 above in that a fluid mixture is introduced through the
inlet port 412, heavy constituent 415 sinks substantially
vertically downward (vertically downward flow of heavy constituent
415) toward lower sidewall 416 and begins convection cell 420 of a
fluid mixture containing a larger portion of heavy constituent 415
flowing downward along the lower sidewall 416 and a fluid mixture
containing the remaining light constituent and a lesser portion, if
any, of the heavy constituent 415 flowing upward along upper
sidewall 418. The fluid mixture containing a larger portion of
heavy constituent 415 flows down the lower sidewall 416 and through
the filter 426. As the fluid mixture flowing down the lower
sidewall 416 and through the filter 426 contains a lesser portion
of the light constituent, the amount of the light constituent that
the filter 426 must remove is less. Accordingly the filter 426 is
less prone to clogging with light constituent and will last longer
than if the filter 426 is used alone without the convection cell
420.
In a configuration where the filter 426 is adapted to filter the
heavy flow and pass the light flow, for example in a configuration
where the filter 426 is positioned above the inlet port 412, the
flow entering the filter 426 has a smaller portion of the heavy
constituent 415, thereby reducing clogging with heavy constituent
415 and increasing the life of the filter 426.
The concepts described herein are not limited to use of a membrane
type filter 426. Rather, numerous other types of filters can be
used, including but not limited to capillary filters, centrifuges,
cyclones, and others. For example, FIG. 5 depicts another alternate
illustrative separator 500 that incorporates a prepacked screen as
a filter 526. A prepacked screen is a screen that carries filter
media, for example a particulate media such as sand, operable to
filter a constituent from the fluid mixture. In an instance of
filtering oil from water, the filter media can be sand that is
treated to be hydrophobic and thereby pass water and filter oil. As
above, the separator 500 is configured to form a convection cell
520 that operates to initially separate the heavy and light
constituents of the fluid mixture prior to filtration of a portion
of the fluid mixture by the filter 526. The filter 526 may be
positioned above or below the inlet port 512. Additionally, the
vessel 510 may include one or more outlet ports 514, for example a
light constituent outlet port 514a about an upper end 522 of the
vessel 510 and a heavy constituent outlet port 514b about a lower
end 524 of the vessel 510.
The filter 526 is cylindrical in configuration and resides adjacent
lower sidewall 516 of the vessel 510. Because the filter 526
resides adjacent the lower sidewall 516, the fluid mixture entering
the filter 526 contains a larger portion of the heavy constituent.
The fluid mixture enters through an upper end wall 528 and/or a
lateral sidewall 530 of the filter 526, passes axially through the
filter 526, and exits about a lower end 532 of the filter 526. The
filter 526 can also be used in conjunction with a bypass mechanism
534, for example a choke or pressure limiting valve, to allow
passage of the fluid mixture should be filter 526 become plugged or
otherwise stopped.
Although several illustrative implementations of the invention have
been described in detail above, those skilled in the art will
readily appreciate that many other variations and modifications are
possible without materially departing from the concepts described
herein. Accordingly, other implementations are intended to fall
within the scope of the invention as defined in the following
claims.
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